1. Technical Field
The described embodiment relates generally to refining polishing operations for cosmetic surfaces of a three dimensional object having cosmetic curved surfaces. More particularly, a method and an apparatus are described for accurately removing material from a curved, cosmetic surface of a housing during a polishing operation.
2. Related Art
Fine surface finishing operations such as sanding and polishing remove material on the order of a few to several hundred microns depending on the intensity and cycles of force application. On three-dimensional surfaces composed of splines or curvatures, it is challenging to measure material removal and directly correlate it to accuracy and efficiency of the finishing operation. During modern machining operations, the finishing tool is generally perpendicular to the curvature of the workpiece whereas historically, measurement methods have been made perpendicular to a plane of reference. This conformal tool orientation results in parallax. Both contact and non-contact measurement methods such as lasers, 3D scanners, CMMs, OMMs, etc. have been deployed in various applications. These methods requires fixed datum as reference with respect to which material removed in the vertical direction compared before and after finishing. Given that the material removed is incredibly small, fixed datums of reference yield a significant measurement error.
Thus there exists a need for a method and an apparatus for polishing a three dimensional curved edge of an object resulting in a visually smooth and consistent reflective appearance.